eMOLT Update 2024-06-14 Weekly RecapThis week, the eMOLT fleet recorded 133 tows of sensorized fishing gear. Bottom temperatures south of Long Island in 14-16 fathoms are in the upper 40s and low 50s (see the plot below) with surface waters in the mid to upper 50s. Similar conditions can be found along the South Shore of Massachusetts.
The southwestern part of Cape Cod Bay has some of the warmest bottom temps we’re seeing at the moment (in the mid-50s). Heading up to Maine, east of Penobscot Bay, temps remain in the mid-40s at the bottom (~40 fathoms), with surface temperatures only a degree or two warmer. George and Huanxin completed a calibration check of the 25 DOT-2 dissolved oxygen and temperature loggers that we have here in the lab. There were a couple hiccups with one logger that may need to go back to the factory for more testing. The other 24 successfully detected hypoxic conditions in the first calibration bath and tracked temperature within fraction of a degree of the reference probe. If you have a Dissolved Oxygen probe, we’ll be reaching out with prepaid envelopes to get those back to us for pre-season calibration checks and new batteries. The plot below shows our temperature test with one probe. The serial number of the DOT-2 probe is shown at the top of the plot. The white circles are a plot of the temperature measured by the Fluke 1523 Calibration Thermometer (x-axis – horizontal) against the temperature measured by a DOT-2 probe (y-axis – vertical). For example, if the Fluke 1523 read 5 degrees, we would expect the DOT-2 probe to also read 5 degrees. The black line is a 1:1 line, so if the DOT-2 probe performed flawlessly, all of the points would be on that line. As you can see, it was slightly off (Root Mean Squared Error of 0.004 degrees C or 0.0072 degrees F) and the estimated relationship between the calibration thermometer temps and the DOT-2 temps is shown by the dashed red line. Our highest Root Mean Squared Error was 0.025 degrees C or 0.045 degrees F.
The second plot that we generated for each logger shows Dissolved Oxygen concentrations (mg/L) over time as the logger was moved between different water baths. In the plot below, you can see open circles that indicate the logger was in air, red circles indicating that the logger was in the low oxygen bath, and blue circles indicating that the logger was in the high oxygen bath. The single blue point in the middle is likely the logger taking some time to equilibrate back to higher dissolved oxygen levels after being in the low DO bath. In the real world, loggers are unlikely to go through this rapid of a shift.
Bottom Longline Survey Photo GalleryThe team from the Gulf of Maine Bottom Longline Survey (a cooperative research survey aboard the F/V Mary Elizabeth and F/V Tenacious II) shared a photo gallery and field blogs from the spring survey season. You can check it out here. System Upgrade ListThe following vessels remain on our list for system upgrades. If you aren’t on the list and think you should be, please reach out.
Bottom Temperature ForecastsDoppioThe Doppio thredds server was upgraded last week, and I need to catch our scripts up to be able to generate the comparison plots, so there’s no comparison plot this week. Thanks to Dr. John Wilkin at Rutgers for giving me a hand moving in the right direction on this front. Hopefully we’ll have the comparisons up and running again next week.
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All the best, -George and JiM |
